Pour milk into a thick-bottomed saucepan, add the cinnamon stick, citrus rind and vanilla extract and bring to a boil. Simmer for several minutes and then discard the cinnamon stick and citrus rind. Set aside.
Whisk the egg yolks in a bowl and add the cornstarch and 3/4 cup of the sugar, whisking until the mixture is creamy. Gradually pour this mixture into the saucepan with the warm milk, whisking continuously so as not to curdle the eggs.
Heat the mixture slowly until it begins to thicken, taking care that the mixture does not boil. Pour into ramekins, small individual clay paella type dishes or heatproof molds. Allow to cool, and refrigerate for several hours.
Just before serving, sprinkle the remaining sugar evenly over each ramekin or mold. If using a salamander, make sure it is red-hot. If using a blow torch, use now to caramelize the sugar.
If using a broiler, turn the broiler on before sprinkling the sugar on top of the dessert. Place the dishes under the broiler until the sugar topping begins to caramelize. Remove from the broiler and serve.